The present invention relates to a multi-joint type industrial robot with a plurality of arms respectively coupled by a plurality of revolvable joints, which is used, for example, for conveying semiconductor wafers in manufacturing process of semiconductor devices.
An industrial robot with a plurality of revolvable joints is conventionally used for conveying works such as semiconductor wafers in a manufacturing facility of semiconductor devices. A configuration of the conventional industrial robot 71 with a plurality of joints is illustrated in FIGS. 7 and 8. In the industrial robot 71, a first motor 73 is provided in a mounting base 72. A first arm 74 is coupled with a drive shaft 73a of the first motor 73 in the vicinity of an end of the first arm 74. A second motor 75 is provided in the vicinity of another end of the first arm 74. A second arm 76 is coupled with a drive shaft 75a of a second motor 75 in the vicinity of an end of the second arm 76. A third motor 77 is provided in the vicinity of another end of the second arm 76. A robotic hand 78 for nipping a work such as a semiconductor wafer is coupled with a drive shaft 77a of the third motor 77 in the vicinity of an end of the robotic hand 78.
The first arm 74 is revolved by rotation force of the first motor 73. The second arm 76 is revolved by rotation force of the second motor 75. The robotic hand 78 is revolved by rotation force of the third motor 77. A sensor 79 for sensing the existence of the work is provided in the vicinity of a top end of the robotic hand 78.
A driving controller 80 is further provided in the mounting base 72. Electric cables 81, 82 and 83 are respectively provided for supplying the electric powers and driving signals to the first to third motors 73, 75 and 77. Furthermore, an electric cable 84 is provided for coupling the sensor 79 and the driving controller 80.
In the conventional industrial robot 71, the electric cables 82 to 84 are directly connected from the driving controller 80 to the motors 75 and 77 and the sensor 79, which are provided on the arms 74 and 76 and the robotic hand 78. When the arms 46 and 76 and the robotic hand 78 are revolved, the electric cables 82 to 84 are bent and/or twisted, or the electric cables 82 to 84 are wound around the arms 74 and 76 and the robotic hand 78. Thus, the electric cables 82 to 84 are easily broken down, and the revolution angles of the arms 74 and 76 and the robotic hand 78 are restricted so that the arms 74 and 76 and the robotic hand 78 cannot revolvable endlessly.
An object of the present invention is to provide an industrial robot with a plurality of joints, by which the electric cables are not bent and twisted, and not wound around the arm or robotic hand so as not to be broken by fatigue of the electric wires, and furthermore, the arms and the robotic hand can be revolved endlessly.
An industrial robot in accordance with an aspect of the present invention has a plurality of arms coupled by a plurality of revolvable joints, each of the arms can be moved by a driving force of a motor which drives each of the revolvable joints. Each of the revolvable joints can be rotated endlessly, and has a rotary electric connecting structure which can be rotated endlessly at least for supplying an electric power from a control circuit to the motor.
By such a configuration, the electric power can be supplied to the motor by the rotary electric connecting structure with using no electric cable while the arm is revolved. Thus, the arm can be revolved endlessly without twisting or breaking of electric cables.